A photon counting type image detector having a semiconductor cell (X-ray detecting material) and a plurality of processing circuits formed by an ASIC layer is used for an X-ray diagnosis apparatus and an X-ray computed tomography apparatus. If X-ray photons each having energy Ein as many as an integer N are absorbed by a certain pixel, it is desirable in an ideal operation of the photon counting type image detector that a signal detected by an incident pixel of the X-ray photons be proportional to Ein times N and that signals on pixels surrounding the incident pixel of the X-ray photons be zero.
According to ordinary technologies, though, as signal leakage into surrounding pixels occurs in a process for detecting X-rays, the signal on the incident pixel of the X-ray photons is not proportional to Ein times N in practice, and a signal on a pixel around the incident pixel of the X-ray photons is not zero.
The fact that a signal appears on a nearby pixel which is different from the incident pixel of the X-ray photons means that space resolution is degraded in image characteristics.
Further, the process in which a signal leaks into a nearby pixel is a stochastic process. Thus, if a plurality of X-ray photons arrives at a certain pixel, results of signal leakage are not the same each time of incidence. This contributes to generating noise on an image in image characteristics.